1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Matrix prodect proof

  1. Sep 27, 2008 #1
    Show that if matrix products AB and BA are both defines, then AB and BA are square matrices:

    Let A = a m*n matrix

    IF AB is defined then B must have n rows (n*?) matrix

    IF BA is defined then B must have m columns making it a n*m matrix

    so BA = (n*m) * (m*n) = (n*n) matrix

    AB = (m*n) * (n*m) = (m*m) matrix

    Show that if A is an m*n matrix and A(BA) is defined, then B is an n*m matrix.

    IF BA is defined and A is m*n matrix then B must be a ?*m matrix

    BA produces a ?*n matrix

    IF A(BA) is defined BA must be a n*n matrix

    AS BA is an n*n matrix B must be a n*m matrix

    Do these work as a proofs, if they even follow any logic in the first place (I'm horrid when it comes to matrices)

    Any input would be greatly appreciated :)
  2. jcsd
  3. Sep 27, 2008 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    They look perfectly good to me.
  4. Sep 27, 2008 #3
    love you :)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Matrix prodect proof
  1. Proofs about Matrix (Replies: 5)

  2. Matrix proof (Replies: 3)

  3. Matrix proof question (Replies: 2)